i) Field of the Invention
The present invention relates to a semiconductor chip with which die bonding or wire bonding is carried out by an automaton, and more particularly to a semiconductor chip having a dummy pattern for preventing peeling of an insulating film formed on the semiconductor chip having a recognition area including a recognition mark having bonding information.
ii) Description of the Related Arts
Conventionally, for example, in an LED head to be mounted on a facsimile machine, a printer or the like, during its production process, wire bonding between an LED chip and an IC is carried out by an automaton. At this time, the automaton is adapted to perform the wire bonding on the basis of a recognition mark provided on the LED chip and information of a recognition area.
This will be described in detail in connection with FIG. 1 to FIG. 3. Generally, a plurality of semiconductor chips 10 such as LED chips or the like with which die bonding or wire bonding are carried out is formed on a wafer and in order to separate the semiconductor chips 10, dicing lines 3 are drawn at their peripheries. The wafer is cut along the dicing lines 3 by a dicing saw rotating at a high speed so as to separate into a plurality of semiconductor chips. In a further process, die bonding of the separated semiconductor chip 10 on a substrate or wire bonding of the semiconductor chip 10 with an IC or the like is carried out by an automaton. At the die bonding or the wire bonding stage, a recognition mark 1 and its surrounding recognition area 2 are used. By binary-coding of a pattern represented by the recognition mark 1 and the recognition area 2, the automaton recognizes the information represented by the pattern and executes the die bonding or the wire bonding in a predetermined position in a predetermined order.
As shown in FIG. 2, when an impurity diffusion layer 4 to become a light emitting part is formed by doping an impurity such as zinc or the like, the recognition mark 1 of the semiconductor chip 10 is formed by the same impurity at the same time. At this time, the recognition mark 1 and the impurity diffusion layer 4 are formed by doping the impurity through diffusion windows 5a opened in parts of an insulating film 5. Further, alternatively, as shown in FIG. 3, when a wiring pattern such as an electrode 6 is formed, the recognition mark 1 is simultaneously formed on the insulating film 5 by an aluminum vapor deposition means or the like.
As will be apparent from FIG. 1, usually, the recognition mark 1 is set near the dicing lines 3 in one corner of the semiconductor chip 10, and as a matter of course, the recognition area 2 including the recognition mark 1 is also positioned near the dicing lines 3. However, the insulating film 5 formed on the surface of the semiconductor chip 10 can be peeled off from an end edge 7 cut at the time of dicing. When the film peeling does not reach the recognition area 2, there is no problem with reading the bonding information. However, as shown in FIGS. 1 and 2, when the film peeling 8 (a hatching area in FIG. 1) reaches the recognition area 2, a recognition error often occurs at the time when the binary-coded information is read by the automaton. In particular, When the film peeling 8 reaches the recognition mark 1, the probability of the recognition error occurring rises sharply. This is considered to be caused because by the film peeling 8, the surface condition of the recognition mark 1 and the recognition area 2 becomes different from normal and the binary-coded information of the recognition mark 1 and the recognition area 2 is changed to cause the recognition error of the automaton.
Further, when the insulating film 5 of the surface is peeled off at the position other than near the recognition mark 1 and the recognition area 2, a defective element of the semiconductor chip 10 having no normal function results, for example, the light emission is caused at the position other than the desired light emitting part or the electrode is short-circuited.